Selecting - how to differentiate "elements"?
There are two ways in edit mode (&#8633; Tab):


Press L while hovering the mouse over the part of the bag you want to select. This will select all the geometry which is connected to the part under your cursor.
Select some geometry (e.g. with  RMB), then press &#9096; CtrlL. This will select all the geometry which is connected to the existing selection.


If you want to separate the parts into separate objects, then press P> Loose parts in edit mode. This will separate disconnected parts of the object into their own objects.